Snoring is the direct consequence that causes the difficulty of the passage of air in the upper airways. The whole area of the throat collapses easily and when the structures that form the so-called “crossroads oropharyngeal” make contact and begin to vibrate causing snoring.
But if this problem is the fact that the person who snores suffers from obesity and therefore has a greater amount of abdominal fat, the ventilation capacity of the thorax decreases.
While you sleep the obese need better ventilated and that is why open your mouth and snores louder than usual. With the addition that the obese tend to sleep face up to its own weight forces him to do so to be more comfortable.